What is the role of intercostal muscles during breathing?

Intercostal muscles play a crucial role in the mechanics of breathing by assisting in the expansion and contraction of the thoracic cavity. When you inhale, these muscles contract, which elevates the ribs and enlarges the chest cavity, resulting in a decrease in internal pressure and allowing air to flow into the lungs. During exhalation, the intercostal muscles relax, helping to reduce the volume of the thoracic cavity, thus increasing the pressure within the lungs and expelling air.

The heart of the breathing process hinges on the ability of the thoracic cavity to adjust in size, and the intercostal muscles are essential for facilitating these changes. This direct contribution to the physical aspect of respiration sets them apart from other physiological functions involved in breathing. Maintaining airway closure and increasing intrathoracic pressure, while important in other scenarios, do not accurately describe the primary role of intercostal muscles in the context of breathing mechanics.